What Are SD Memory Cards

SD memory cards (Secure Digital) cards are a family of memory developed from the MMC that are most prevalent in the market and can find them in all sorts of devices like digital cameras, PDAs, mobile phones, laptops or consoles. The range of SD memory cards consists of four standards: SDSC (Standard Capacity SD), SDHC (SD High Capacity), SDXC (SD Extended Capacity) and SDIO (SD Input Output), available in three sizes: SD, miniSD and microSD.

Applications

SD memory cards (Secure Digital) were developed from the MMC (MultiMediaCard) format and are currently the dominant memory card and has become the de facto standard in the industry, so there are plenty of electronic devices incorporating memory card reader SD, as digital cameras, game consoles, camcorders, PDAs, laptops or mobile phones.

Standards

The formats of memory cards SD Secure Digital develops the Card Association, there are four standards:

SDSC (Secure Digital Standard Capacity): The original SD 1.0 standard, known as SD, maximum capacity is 2 GB, although some manufacturers extended up to 4 GB.SDHC (Secure Digital High Capacity): SD version 2.0 determines a capacity of 4-32 GB.SDXC (Secure Digital Extended Capacity): SD 3.0 standard provides a capacity of 32 GB and 2 TB.SDIO (Secure Digital Input Output): the SDIO standard SD slots can use the interface to connect devices such as GPS receivers, Wi-Fi adapter or Bluetooth, barcode readers, fingerprint scanners, modems or TV tuners or FM radio.

Each of the standards SDSC / SDHC / SDXC / SDIO provides different communication protocols, so that although modern readers implement backwards compatibility with previous versions, older readers will not recognize the new card or if they do will be limited to 2 GB or 4 GB, not being able to write correctly in higher capacity cards, which may result in data loss. Some older drives can support SDHC by updating the firmware.

Dimensions

Regarding the dimensions and form factors of SD memory cards, there are three sizes:

SD: 32x24x2.1 mmminiSD: 21.5x20x1.4 mmmicroSD: 15x11x0.7 mm

File System

Generally, SD memory cards are formatted FAT16, SDHC cards while usually formatted as FAT32. Although both types of cards can support other file systems is not recommended to change the file system nor reformat the card, which can cause performance problems, incompatibility or affect the life of the card.

Readers

You can access the SD card content with a specific reader or using a USB adapter. The smaller size cards, miniSD and microSD can be used in SD slots with adapters, which are basically passive devices electrically connecting the pins of the card and the SD slot.